節點郵件錯誤：發送後無法設置標題

Question

我嘗試在創建新資源後嘗試發送郵件，並且在創建新用戶之前，應檢查電子郵件和員工編號，如果其中任何一個值相同顯示已存在，否則將添加新資源併發送郵件。

如果email和emp不一樣，它完全創建資源併發送郵件。但是，如果我試圖同一個郵件或EMP數量正在逐漸錯誤

我的錯誤：

events.js:182 
     throw er; // Unhandled 'error' event 
    ^

Error: Can't set headers after they are sent. 
    at validateHeader (_http_outgoing.js:489:11) 
    at ServerResponse.setHeader (_http_outgoing.js:496:3) 
    at ServerResponse.header (D:\hourmint\node_modules\express\lib\response.js:7 
30:10) 
    at ServerResponse.location (D:\hourmint\node_modules\express\lib\response.js 
:847:15) 
    at ServerResponse.redirect (D:\hourmint\node_modules\express\lib\response.js 
:885:18) 
    at D:\hourmint\app\routes.js:298:18 
    at D:\hourmint\node_modules\mongoose\lib\query.js:2917:18 
    at <anonymous> 
    at process._tickCallback (internal/process/next_tick.js:188:7) 

我變送器：

var smtpTransport = nodemailer.createTransport({ 
    service: 'Gmail', 
    auth: { 
    user: 'noemail@gmail.com', 
    pass: 'mypassword' 
    }, 
}); 

我的代碼：

app.post('/addresources', isLoggedIn, function(req, res) { 
    var id = (req.body._id) ? req.body._id : mongoose.Types.ObjectId(0); 
    var newPwd = new mongo.resource(); 

    var pwd = newPwd.generateHash(req.body.res_password); 
    var resourceValue = { 
    'role_id': req.body.role_id, 
    'privilege_id': req.body.privilege_id, 
    'res_fname': req.body.res_fname, 
    'res_lname': req.body.res_lname, 
    'res_email': req.body.res_email, 
    'res_password': pwd, 
    'res_empno': req.body.res_empno, 
    'res_city': req.body.res_city, 
    'res_mobile': req.body.res_mobile, 
    'res_emerno': req.body.res_emerno, 
    'res_hourlyrate': req.body.res_hourlyrate, 
    'res_otp': 0, 
    'res_status': req.body.res_status 
    }; 

    mongo.resource.findOne({ 
    $or: [{ 
     'res_email': req.body.res_email 
    }, { 
     'res_empno': req.body.res_empno 
    }] 
    }).exec(function(err, user) { 
    if (err) throw err; 
    if (user) { 
     console.log(user) 
     if (user.res_email == req.body.res_email && user.res_empno == req.body.res_empno) { 

     req.flash('error', 'Email And Employee Number Already Exists!!!') 
     res.redirect('/resources') 


     } //user already exists with email AND/OR phone. 
     else if (user.res_email == req.body.res_email) { 

     req.flash('error', 'Email Id Already Exists!!!') 
     res.redirect('/resources') 


     } //no users with that email NOR phone exist. 
     else(user.res_empno == req.body.res_empno) { 

     req.flash('error', 'Employee Number Already Exists!!!') 
     res.redirect('/resources') 

     } 
    } else { 


     mongo.resource.findOneAndUpdate({ 
     '_id': id 
     }, resourceValue, { 
     upsert: true, 
     new: true 
     }, function(err, response) { 
     if (err) throw err; 


     console.log("Resource Added SuccessFully") 
     console.log(response.res_email) 
     res.redirect('/resources') 

     var mainOptions = { 
      from: '"Niyati" <noemail@gmail.com>', 
      to: response.res_email, 
      subject: 'Hello ✔', // Subject line 
      text: 'Hello world ?', // plaintext body 
      html: '<b>Hello world ?</b>' // html body 
     }; 
     //console.log("html data ======================>", mainOptions.html); 
     smtpTransport.sendMail(mainOptions, function(err, info) { 
      if (err) throw err; 
      console.log("mail Sent"); 
      // console.log(err); 
     }); 

     }); 
    } 
    }); 
}); 

Answer 1

問題引起由於你的其他條件存在缺陷。當第一，如果匹配

user.res_email == req.body.res_email && user.res_empno == req.body.res_empno

的else if語句將匹配也是如此。所以res.redirect被觸發兩次。

請優化您的if/else條件以確保沒有重疊。